Mario Contin

Lithocholic acid as a biomarker of intrahepatic cholestasis of pregnancy during ursodeoxycholic acid treatment

Background The diagnosis and treatment of intrahepatic cholestasis of pregnancy (ICP) has important implications on fetal health. The biochemical parameter commonly used in the diagnosis of ICP is the determination of the concentration of total serum bile acids (TSBA). However, bile acid profile, especially lithocholic acid (LCA) analysis is a more sensitive and specific biomarker for differential diagnosis of this pathology and also could be an alternative to evaluate the efficiency of ursodeoxycholic acid (UDCA) for ICP treatment. Methods Serum bile acid (SBA) profiles including LCA determination, were studied in 28 ICP patients using a capillary electrophoresis method. The effects of UDCA treatment on bile acid profile, were analysed in 23 out of 28 ICP patients and the two samples obtained before and 15 days after treatment were compared. Two samples taken as controls were also obtained from each of five patients without therapy. Results A dramatic decrease in LCA concentrations and maintenance of TSBA concentrations were found in all patients after UDCA therapy, whereas SBA profiles together with LCA values did not change in patients without therapy. Conclusion We propose LCA as an alternative biomarker and a more sensitive parameter than TSBA to evaluate the effectiveness of UDCA treatment, at least in ICP patients from Argentina.

Simultaneous determination of nine endogenous steroids in human urine by polymeric-mixed micelle capillary electrophoresis.

A new CE system based on the use of polymeric‐mixed micelles (cholic acid, SDS and the poloxamine Tetronic® 1107) was developed for the simultaneous determination of nine steroids in human urine. This method allows the baseline separation and quantitation of cortisol, androstenedione, estriol, dehydroepiandrosterone sulfate, testosterone, dehydroepiandrosterone, estrone, progesterone and estradiol in less than 25 min showing to be sensitive enough to detect low concentrations of these steroids in urine samples (5–45 ng/mL). The optimized electrophoretic conditions were performed using a 50 cm×75 μm capillary, 18 kV, 25°C, with 44 mM cholic acid, 10 mM SDS, 0.05% w/v tetronic® 1107, 2.5% v/v methanol, 2.5% v/v tetrahydrofuran in 5 mM borate – 5 mM phosphate buffer (pH=8.0) as a background electrolyte and a dual 210/254 UV‐detection. The method can simultaneously determine 0.1–120 μg/mL, which corresponds to 5–6000 ng/mL of steroids in 2 mL urine. The recoveries ranged between 82.4 and 101.5%. Due to its simplicity, speed, accuracy and reliability, the proposed method could be a potential alternative to the traditional methodologies used with clinical purposes.

The use of coenzyme Q0 as a template in the development of a molecularly imprinted polymer for the selective recognition of coenzyme Q10.

In this work, a novel molecularly imprinted polymer (MIP) for use as a solid phase extraction sorbent was developed for the determination of coenzyme Q10 (CoQ10) in liver extract. CoQ10 is an essential cofactor in mitochondrial oxidative phosphorylation and a powerful antioxidant agent found in low concentrations in biological samples. This fact and its high hydrophobicity make the analysis of CoQ10 technically challenging. Accordingly, a MIP was synthesised using coenzyme Q0 as the template, methacrylic acid as the functional monomer, acetonitrile as the porogen, ethylene glycol dimethacrylate as the crosslinker and benzoyl peroxide as the initiator. Various parameters affecting the polymer preparation and extraction efficiency were evaluated. Morphological characterisation of the MIP and its proper comparison with C18 as a sorbent in solid phase extraction were performed. The optimal conditions for the molecularly imprinted solid phase extraction (MISPE) consisted of 400 μL of sample mixed with 30 mg of MIP and 600 μL of water to reach the optimum solution loading. The loading was followed by a washing step consisting of 1 mL of a 1-propanol solution (1-propanol:water, 30:70,v/v) and elution with 1 mL of 1-propanol. After clean-up, the CoQ10 in the samples was analysed by high performance liquid chromatography. The extraction recoveries were higher than 73.7% with good precision (3.6-8.3%). The limits of detection and quantification were 2.4 and 7.5 μg g(-1), respectively, and a linear range between 7.5 and 150 μg g(-1) of tissue was achieved. The new MISPE procedure provided a successful clean-up for the determination of CoQ10 in a complex matrix.

MINIATURIZED HPLC-UV METHOD FOR ANALYSIS OF COENZYME Q10 IN HUMAN PLASMA

Coenzyme Q10 (CoQ10) is a cofactor in the respiratory chain and a potent endogenous antioxidant. Abnormally low levels of CoQ10 in the circulatory system are often involved with pathological states such as heart failure, mitochondrial and muscular diseases, and cancer. The development of simple, rapid, and highly sensitive methods capable of quantifying low CoQ10 levels in plasma is, therefore, increasingly required. In this work, we developed a miniaturized HPLC-UV system for the determination CoQ10 in human plasma using an XTerra microcolumn (50 mm × 2.1 mm i.d., 3.5 µm particle size), methanol:water (98:2, v/v) as mobile phase, 275 nm, flow rate of 0.3 mL/min, 30 °C column temperature, and 2 µL injection volume. The extraction procedure consists of a plasma precipitation with 1-propanol and evaporation under nitrogen to allow a 1.5-fold enrichment. The chromatographic analysis was accomplished in 7 min. As a result, it was possible to quantitate CoQ10 in small sample volumes down to 0.07 µM and detect as low as 0.02 µM in real plasma, with good accuracy and precision, even in pathological conditions. The proposed method was found to be suitable for routine CoQ10 determination in clinical laboratories.

Simple, Highly Sensitive Micro HPLC Method for the Determination of Coenzyme Q10 and its Major Related Substances

Abstract A simiple, rapid, and highly sensitive fast microbore HPLC method with UV detection has been developed for the quantitation of coenzyme Q10 (Co-Q10) and related substances in raw material, pharmaceutical, and cosmetic formulations using a column with hybrid particles. Chromatographic conditions were: 30ºC column temperature, 1 µL injection volume at 275 nm. The Co-Q10 analysis was performed within 2.5 minutes with a flow rate of 0.3 mL/min. with a mobile phase consisted of 100% methanol, and the related substances were separated with a gradient elution based on methanol-water. The developed method was validated for selectivity, linearity, precision, accuracy, and robutness. The method was found to be suitable for the quality control of Co-Q10 in pharmaceutical and cosmetic products, as well as the stability indicating studies.

Novel and highly sensitive mixed-polymeric electrokinetic chromatography system for determination of contaminants and impurities of heparin samples

A mixed‐polymeric electrokinetic chromatography system has been developed for the simultaneous determination of a contaminant like oversulfated condroitin sulfate (OSCS) and impurities expressed as dermatan (Der) in heparin (Hep) samples. The EKC system consisted of 0.5% w/v polymeric β‐CD, 0.4% w/v tetronic® 1107 and 400 mM tris‐phosphate buffer at pH 3.5. The optimized electrophoretic conditions included the use of an uncoated‐silica capillary of 50 cm of total length and 75 μm id, an applied voltage of −7 kV, a temperature of 30°C and 200 nm UV‐detection. The highly sensitive method developed showed low values of LOD, 0.07% w/w (0.07 μg/mL) (OSCS) and 0.1% w/w (0.1 μg/mL) (Der), and values of LOQ 0.2% w/w (0.2 μg/mL) (OSCS) and 0.3% w/w (0.3 μg/mL) (Der) with a concentration level of Hep sample as low as 0.1 mg/mL. Additional parameters of validation such as specificity, linearity, accuracy, and robustness were evaluated according to international guidelines. Owing to its simplicity, high sensitivity, and reliability, the proposed method can be an advantageous alternative to the traditional methodologies for the analysis of Hep in raw material and specially in finished products because of the low amounts of Hep sample required.

Synthesis and characterization of molecularly imprinted polymer nanoparticles for coenzyme Q10 dispersive micro solid phase extraction.

Molecularly imprinted polymer nanoparticles (MIPNPs) with the ability to recognize coenzyme Q10 (CoQ10) were synthesised in order to be employed as sorbent in a dispersive micro-solid phase extraction (DMSPE) for the determination of CoQ10 in a liver extract. CoQ10 is a redox-active, lipophilic substance integrated in the mitochondrial respiratory chain which acts as an electron carrier, shuttling electrons from complex I (NADH-ubiquinone oxidoreductase) and II (succinate-ubiquinone oxidoreductase) to complex III (ubiquinol-cytochrome c reductase), for the production of cellular energy. The MIPNPs were synthesised by precipitation polymerization using coenzyme Q0 as the dummy template, methacrylic acid as the functional monomer, an acetonitrile: water mixture as the porogen, ethylene glycol dimethacrylate as the crosslinker and potassium persulfate as initiator. The nanoparticles were characterized by microscopy, capillary electrophoresis, dynamic light scattering, N2 adsorption-desorption isotherms, and infrared spectroscopy. The MIPNPs demonstrated the presence of selective cavities complementary to the quinone nucleus of CoQ10, leading to a specific recognition of CoQ10 compared with related compounds. In the liver extract the relative CoQ10 peak area (CoQ10 area/total peak area) increased from 4.6% to 25.4% after the DMSPE procedure. The recovery percentage of CoQ10 from the liver matrix was between 70.5% and 83.7% quantified against CoQ10 standard processed under the same conditions. The DMSPE procedure allows the elution of almost all the CoQ10 retained (99.4%) in a small volume (200μL), allowing the sample to be concentrated 2.5 times (LOD: 1.1μgg(-1) and LOQ: 3.7μgg(-1) of tissue). The resulted clean up of the sample, the improvement in peak shape and baseline and the reduction of interferences, evidence that the MIPNPs could potentially be applied as sorbent in a DMSPE with satisfactory results and with a minimum amount of sorbent (1mg).

New analytical strategies applied to the determination of Coenzyme Q10 in biological matrix.

In the last few years the importance of Coenzyme Q10 (CoQ10) determination has gained clinical relevance. CoQ10 is a redox-active, lipophilic substance integrated in the mitochondrial respiratory chain which acts as an electron carrier for the production of cellular energy. In addition, it is recognized as a primary regenerating antioxidant playing an intrinsic role against oxidative damage. There are some reports of low CoQ10 levels in a number of disorders, such as cancer, muscular, neurodegenerative, cardiological, and reproductive diseases. Therefore, it is a priority to develop analytical methodologies for evaluating CoQ10 in matrices of greater importance for the correct diagnosis of diseases, simple enough to be used in routine clinical laboratories. In this chapter two recently developed techniques, capillary electrophoresis and microHPLC, for the analysis of CoQ10 in biological matrices, are studied.

Molecularly Imprinted Solid Phase Extraction Before Capillary Electrophoresis for the Analysis of Estrogens in Serum Samples

Fil: Contin, Mario Daniel. Universidad de Buenos Aires. Facultad de Farmacia y Bioquimica. Departamento de Quimica Analitica y Fisicoquimica. Catedra de Quimica Analitica; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Houssay; Argentina

In Search of an Accurate Evaluation of Intrahepatic Cholestasis of Pregnancy

Until now, biochemical parameter for diagnosis of intrahepatic cholestasis of pregnancy (ICP) mostly used is the rise of total serum bile acids (TSBA) above the upper normal limit of 11 μM. However, differential diagnosis is very difficult since overlapped values calculated on bile acids determinations, are observed in different conditions of pregnancy including the benign condition of pruritus gravidarum. The aim of this work was to determine the better markers in ICP for a precise diagnosis together with parameters associated with severity of symptoms and treatment evaluation. Serum bile acid profiles were evaluated using capillary electrophoresis in 38 healthy pregnant women and 32 ICP patients and it was calculated the sensitivity, specificity, accuracy, predictive values and the relationships of certain individual bile acids in pregnant women in order to replace TSBA determinations. The evaluation of the results shows that LCA and UDCA/LCA ratio provided information for a more complete and accurate diagnosis and evaluation of ICP than calculation of solely TSBA levels in pregnant women.